Oops

Programming prototype based on the concept of objects

Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which tin contain data and lawmaking: data in the form of fields (often known equally attributes or backdrop), and code, in the form of procedures (ofttimes known equally methods).

A feature of objects is that an object'due south own procedures can access and often change the data fields of itself (objects have a notion of this or self ). In OOP, computer programs are designed past making them out of objects that interact with ane some other.^[1] ^[2] OOP languages are diverse, but the well-nigh popular ones are class-based, meaning that objects are instances of classes, which also determine their types.

Many of the well-nigh widely used programming languages (such as C++, Java, Python, etc.) are multi-paradigm and they back up object-oriented programming to a greater or lesser degree, typically in combination with imperative, procedural programming. Pregnant object-oriented languages include: Coffee, C++, C#, Python, R, PHP, Visual Basic.NET, JavaScript, Ruby, Perl, SIMSCRIPT, Object Pascal, Objective-C, Dart, Swift, Scala, Kotlin, Mutual Lisp, MATLAB, and Smalltalk.

History [edit]

UML annotation for a class. This Push button class has variables for data, and functions. Through inheritance a subclass can be created as subset of the Button class. Objects are instances of a class.

Terminology invoking "objects" and "oriented" in the modern sense of object-oriented programming made its outset appearance at MIT in the late 1950s and early on 1960s. In the environment of the bogus intelligence grouping, as early as 1960, "object" could refer to identified items (LISP atoms) with properties (attributes);^[3] ^[four] Alan Kay later cited a detailed understanding of LISP internals every bit a strong influence on his thinking in 1966.^[v]

I idea of objects being like biological cells and/or individual computers on a network, just able to communicate with messages (and so messaging came at the very beginning – information technology took a while to run across how to do messaging in a programming language efficiently enough to be useful).

Alan Kay, ^[5]

Another early MIT example was Sketchpad created past Ivan Sutherland in 1960–1961; in the glossary of the 1963 technical report based on his dissertation near Sketchpad, Sutherland defined notions of "object" and "instance" (with the class concept covered by "master" or "definition"), albeit specialized to graphical interaction.^{[half dozen]} Besides, an MIT ALGOL version, AED-0, established a direct link betwixt information structures ("plexes", in that dialect) and procedures, prefiguring what were later termed "messages", "methods", and "member functions".^[7] ^[eight]

Simula introduced important concepts that are today an essential office of object-oriented programming, such as class and object, inheritance, and dynamic bounden.^[9] The object-oriented Simula programming linguistic communication was used mainly by researchers involved with physical modelling, such as models to study and meliorate the movement of ships and their content through cargo ports.^[9]

In the 1970s, the start version of the Smalltalk programming language was developed at Xerox PARC by Alan Kay, Dan Ingalls and Adele Goldberg. Smalltalk-72 included a programming surround and was dynamically typed, and at first was interpreted, not compiled. Smalltalk became noted for its application of object orientation at the language-level and its graphical development surroundings. Smalltalk went through various versions and interest in the language grew.^[x] While Smalltalk was influenced by the ideas introduced in Simula 67 information technology was designed to be a fully dynamic system in which classes could be created and modified dynamically.^[11]

In the 1970s, Smalltalk influenced the Lisp community to incorporate object-based techniques that were introduced to developers via the Lisp machine. Experimentation with various extensions to Lisp (such as LOOPS and Flavors introducing multiple inheritance and mixins) eventually led to the Common Lisp Object System, which integrates functional programming and object-oriented programming and allows extension via a Meta-object protocol. In the 1980s, at that place were a few attempts to design processor architectures that included hardware support for objects in memory simply these were not successful. Examples include the Intel iAPX 432 and the Linn Smart Rekursiv.

In 1981, Goldberg edited the August issue of Byte Magazine, introducing Smalltalk and object-oriented programming to a wider audience. In 1986, the Clan for Computing Machinery organised the first Conference on Object-Oriented Programming, Systems, Languages, and Applications (OOPSLA), which was unexpectedly attended by 1,000 people. In the mid-1980s Objective-C was developed by Brad Cox, who had used Smalltalk at ITT Inc., and Bjarne Stroustrup, who had used Simula for his PhD thesis, eventually went to create the object-oriented C++.^[10] In 1985, Bertrand Meyer also produced the first design of the Eiffel language. Focused on software quality, Eiffel is a purely object-oriented programming language and a annotation supporting the entire software lifecycle. Meyer described the Eiffel software development method, based on a small number of cardinal ideas from software engineering and computer science, in Object-Oriented Software Construction. Essential to the quality focus of Eiffel is Meyer'south reliability machinery, Pattern by Contract, which is an integral part of both the method and linguistic communication.

In the early on and mid-1990s object-oriented programming developed as the dominant programming epitome when programming languages supporting the techniques became widely bachelor. These included Visual FoxPro 3.0,^[12] ^[13] ^[14] C++,^[15] and Delphi^{[ citation needed ]}. Its authority was further enhanced by the ascension popularity of graphical user interfaces, which rely heavily upon object-oriented programming techniques. An case of a closely related dynamic GUI library and OOP language can be institute in the Cocoa frameworks on Mac OS X, written in Objective-C, an object-oriented, dynamic messaging extension to C based on Smalltalk. OOP toolkits as well enhanced the popularity of event-driven programming (although this concept is not limited to OOP).

At ETH Zürich, Niklaus Wirth and his colleagues had also been investigating such topics equally data abstraction and modular programming (although this had been in common use in the 1960s or earlier). Modula-2 (1978) included both, and their succeeding blueprint, Oberon, included a distinctive approach to object orientation, classes, and such.

Object-oriented features take been added to many previously existing languages, including Ada, BASIC, Fortran, Pascal, and COBOL. Adding these features to languages that were not initially designed for them often led to problems with compatibility and maintainability of code.

More recently, a number of languages have emerged that are primarily object-oriented, but that are likewise uniform with procedural methodology. Two such languages are Python and Crimson. Probably the most commercially important contempo object-oriented languages are Coffee, adult by Sunday Microsystems, also as C# and Visual Basic.Internet (VB.Cyberspace), both designed for Microsoft's .Net platform. Each of these 2 frameworks shows, in its own way, the do good of using OOP by creating an abstraction from implementation. VB.Internet and C# support cross-linguistic communication inheritance, allowing classes defined in ane linguistic communication to subclass classes defined in the other language.

Features [edit]

Object-oriented programming uses objects, but not all of the associated techniques and structures are supported direct in languages that merits to support OOP. It performs operations on operands. The features listed below are common among languages considered to exist strongly class- and object-oriented (or multi-epitome with OOP support), with notable exceptions mentioned.^[sixteen] ^[17] ^[18] ^[19]

Shared with non-OOP languages [edit]

Variables that tin can store information formatted in a small number of built-in data types similar integers and alphanumeric characters. This may include data structures similar strings, lists, and hash tables that are either congenital-in or upshot from combining variables using retentivity pointers.
Procedures – too known as functions, methods, routines, or subroutines – that accept input, generate output, and manipulate data. Mod languages include structured programming constructs similar loops and conditionals.

Modular programming back up provides the ability to grouping procedures into files and modules for organizational purposes. Modules are namespaced then identifiers in i module will non conflict with a procedure or variable sharing the same name in some other file or module.

Objects and classes [edit]

Languages that back up object-oriented programming (OOP) typically use inheritance for lawmaking reuse and extensibility in the form of either classes or prototypes. Those that use classes back up two main concepts:

Classes – the definitions for the data format and available procedures for a given type or class of object; may too contain data and procedures (known as class methods) themselves, i.e. classes incorporate the data members and fellow member functions
Objects – instances of classes

Objects sometimes correspond to things plant in the real globe. For instance, a graphics programme may have objects such every bit "circumvolve", "square", "menu". An online shopping system might have objects such every bit "shopping cart", "customer", and "production".^[20] Sometimes objects represent more abstract entities, like an object that represents an open file, or an object that provides the service of translating measurements from U.Due south. customary to metric.

Each object is said to exist an example of a particular course (for example, an object with its proper name field set to "Mary" might exist an instance of class Employee). Procedures in object-oriented programming are known equally methods; variables are likewise known as fields, members, attributes, or properties. This leads to the following terms:

Class variables – belong to the class as a whole; there is only i re-create of each one
Instance variables or attributes – data that belongs to private objects; every object has its own copy of each one
Member variables – refers to both the class and case variables that are defined by a item class
Class methods – belong to the course equally a whole and accept access to only class variables and inputs from the process phone call
Instance methods – belong to individual objects, and take access to instance variables for the specific object they are called on, inputs, and class variables

Objects are accessed somewhat like variables with complex internal structure, and in many languages are effectively pointers, serving as actual references to a single case of said object in retentiveness within a heap or stack. They provide a layer of abstraction which can be used to dissever internal from external code. External code can utilize an object by calling a specific instance method with a certain fix of input parameters, read an example variable, or write to an instance variable. Objects are created past calling a special type of method in the class known as a constructor. A program may create many instances of the same grade as it runs, which operate independently. This is an easy way for the same procedures to be used on different sets of data.

Object-oriented programming that uses classes is sometimes called class-based programming, while prototype-based programming does non typically use classes. As a result, significantly unlike still analogous terminology is used to define the concepts of object and instance.

In some languages classes and objects tin can exist composed using other concepts like traits and mixins.

Class-based vs paradigm-based [edit]

In course-based languages the classes are divers beforehand and the objects are instantiated based on the classes. If two objects apple tree and orangish are instantiated from the class Fruit, they are inherently fruits and it is guaranteed that you may handle them in the aforementioned style; e.thousand. a programmer can expect the existence of the aforementioned attributes such as color or sugar_content or is_ripe.

In image-based languages the objects are the primary entities. No classes even exist. The prototype of an object is but another object to which the object is linked. Every object has one prototype link (and only one). New objects can be created based on already existing objects called every bit their epitome. You may call 2 unlike objects apple tree and orangish a fruit, if the object fruit exists, and both apple and orange have fruit as their prototype. The idea of the fruit class doesn't exist explicitly, just as the equivalence grade of the objects sharing the same prototype. The attributes and methods of the prototype are delegated to all the objects of the equivalence class divers by this prototype. The attributes and methods owned individually by the object may non be shared by other objects of the aforementioned equivalence form; east.g. the aspect sugar_content may be unexpectedly non present in apple. Only single inheritance can be implemented through the image.

Dynamic dispatch/message passing [edit]

It is the responsibility of the object, not whatever external code, to select the procedural code to execute in response to a method call, typically by looking upwards the method at run time in a tabular array associated with the object. This feature is known as dynamic acceleration. If the call variability relies on more than than the single blazon of the object on which information technology is called (i.e. at to the lowest degree one other parameter object is involved in the method choice), one speaks of multiple dispatch.

A method telephone call is besides known as message passing. It is conceptualized as a bulletin (the name of the method and its input parameters) being passed to the object for acceleration.

Data Brainchild [edit]

Data Abstraction is a design design in which data are visible merely to semantically related functions, and then as to forbid misuse. The success of information abstraction leads to frequent incorporation of data hiding every bit a design principle in object oriented and pure functional programming.

If a grade does non allow calling lawmaking to access internal object information and permits access through methods only, this is a potent course of brainchild or information hiding known as abstraction. Some languages (Coffee, for example) permit classes enforce admission restrictions explicitly, for example denoting internal data with the private keyword and designating methods intended for use by lawmaking outside the form with the public keyword. Methods may besides exist designed public, private, or intermediate levels such every bit protected (which allows access from the same class and its subclasses, but not objects of a different grade). In other languages (like Python) this is enforced only by convention (for case, private methods may have names that start with an underscore).

          Encapsulation

Encapsulation prevents external code from being concerned with the internal workings of an object.  This facilitates lawmaking refactoring, for example allowing the author of the class to change how objects of that class stand for their information internally without changing any external lawmaking (equally long as "public" method calls work the same way).  Information technology too encourages programmers to put all the code that is concerned with a certain set of information in the same class, which organizes it for easy comprehension by other programmers.  Encapsulation is a technique that encourages decoupling.

Limerick, inheritance, and delegation [edit]

Objects can comprise other objects in their instance variables; this is known as object composition. For example, an object in the Employee grade might contain (either directly or through a pointer) an object in the Address class, in addition to its own instance variables like "first_name" and "position". Object composition is used to represent "has-a" relationships: every employee has an accost, so every Employee object has access to a place to store an Accost object (either straight embedded inside itself, or at a separate location addressed via a arrow).

Languages that support classes nearly always support inheritance. This allows classes to be arranged in a hierarchy that represents "is-a-blazon-of" relationships. For instance, class Employee might inherit from class Person. All the information and methods available to the parent course as well announced in the child class with the aforementioned names. For example, form Person might define variables "first_name" and "last_name" with method "make_full_name()". These will also be bachelor in form Employee, which might add the variables "position" and "salary". This technique allows easy re-use of the same procedures and information definitions, in addition to potentially mirroring existent-world relationships in an intuitive manner. Rather than utilizing database tables and programming subroutines, the developer utilizes objects the user may be more familiar with: objects from their application domain.^[21]

Subclasses tin can override the methods defined past superclasses. Multiple inheritance is allowed in some languages, though this can make resolving overrides complicated. Some languages have special support for mixins, though in any language with multiple inheritance, a mixin is simply a grade that does not represent an is-a-type-of relationship. Mixins are typically used to add the same methods to multiple classes. For instance, class UnicodeConversionMixin might provide a method unicode_to_ascii() when included in class FileReader and class WebPageScraper, which don't share a common parent.

Abstract classes cannot be instantiated into objects; they be just for the purpose of inheritance into other "physical" classes that can exist instantiated. In Java, the final keyword can exist used to forbid a class from being subclassed.

The doctrine of composition over inheritance advocates implementing has-a relationships using composition instead of inheritance. For example, instead of inheriting from class Person, class Employee could requite each Employee object an internal Person object, which information technology then has the opportunity to hide from external code even if class Person has many public attributes or methods. Some languages, like Get practice not support inheritance at all.

The "open/closed principle" advocates that classes and functions "should be open for extension, but airtight for modification".

Delegation is some other linguistic communication characteristic that can be used every bit an alternative to inheritance.

Polymorphism [edit]

Subtyping – a grade of polymorphism – is when calling code tin be contained of which form in the supported bureaucracy it is operating on – the parent form or one of its descendants. Meanwhile, the aforementioned operation name among objects in an inheritance hierarchy may behave differently.

For example, objects of type Circle and Square are derived from a common class chosen Shape. The Depict function for each type of Shape implements what is necessary to draw itself while calling code can remain indifferent to the particular type of Shape being drawn.

This is some other type of abstraction that simplifies code external to the course bureaucracy and enables strong separation of concerns.

Open recursion [edit]

In languages that support open recursion, object methods can call other methods on the aforementioned object (including themselves), typically using a special variable or keyword called this or self. This variable is late-leap; it allows a method defined in one class to invoke another method that is defined later on, in some subclass thereof.

OOP languages [edit]

Simula (1967) is generally accepted equally being the starting time language with the primary features of an object-oriented language. It was created for making simulation programs, in which what came to exist called objects were the most important information representation. Smalltalk (1972 to 1980) is another early example, and the ane with which much of the theory of OOP was developed. Concerning the degree of object orientation, the following distinctions can exist made:

Languages called "pure" OO languages, because everything in them is treated consistently as an object, from primitives such every bit characters and punctuation, all the fashion upwardly to whole classes, prototypes, blocks, modules, etc. They were designed specifically to facilitate, even enforce, OO methods. Examples: Carmine, Scala, Smalltalk, Eiffel, Emerald,^[22] JADE, Self, Raku.
Languages designed mainly for OO programming, but with some procedural elements. Examples: Java, Python, C++, C#, Delphi/Object Pascal, VB.NET.
Languages that are historically procedural languages, but have been extended with some OO features. Examples: PHP, Perl, Visual Bones (derived from Basic), MATLAB, COBOL 2002, Fortran 2003, ABAP, Ada 95, Pascal.
Languages with most of the features of objects (classes, methods, inheritance), but in a distinctly original course. Examples: Oberon (Oberon-one or Oberon-two).
Languages with abstract data blazon support which may exist used to resemble OO programming, but without all features of object-orientation. This includes object-based and prototype-based languages. Examples: JavaScript, Lua, Modula-2, CLU.
Chameleon languages that support multiple paradigms, including OO. Tcl stands out among these for TclOO, a hybrid object system that supports both paradigm-based programming and class-based OO.

OOP in dynamic languages [edit]

In contempo years, object-oriented programming has go specially popular in dynamic programming languages. Python, PowerShell, Ruby and Peachy are dynamic languages congenital on OOP principles, while Perl and PHP have been adding object-oriented features since Perl v and PHP 4, and ColdFusion since version vi.

The Certificate Object Model of HTML, XHTML, and XML documents on the Cyberspace has bindings to the popular JavaScript/ECMAScript linguistic communication. JavaScript is peradventure the best known prototype-based programming language, which employs cloning from prototypes rather than inheriting from a class (contrast to class-based programming). Another scripting linguistic communication that takes this approach is Lua.

OOP in a network protocol [edit]

The messages that flow betwixt computers to asking services in a client-server environment can be designed as the linearizations of objects defined past class objects known to both the client and the server. For case, a simple linearized object would consist of a length field, a code point identifying the form, and a data value. A more complex example would be a command consisting of the length and code point of the control and values consisting of linearized objects representing the control's parameters. Each such command must be directed by the server to an object whose class (or superclass) recognizes the command and is able to provide the requested service. Clients and servers are best modeled as complex object-oriented structures. Distributed Information Management Architecture (DDM) took this arroyo and used class objects to define objects at iv levels of a formal hierarchy:

Fields defining the information values that form letters, such as their length, code point and data values.
Objects and collections of objects like to what would exist found in a Smalltalk program for messages and parameters.
Managers similar to IBM i Objects, such every bit a directory to files and files consisting of metadata and records. Managers conceptually provide memory and processing resources for their contained objects.
A customer or server consisting of all the managers necessary to implement a full processing environment, supporting such aspects every bit directory services, security and concurrency command.

The initial version of DDM divers distributed file services. It was later extended to be the foundation of Distributed Relational Database Architecture (DRDA).

Design patterns [edit]

Challenges of object-oriented design are addressed by several approaches. Almost common is known equally the design patterns codified past Gamma et al.. More broadly, the term "design patterns" can be used to refer to whatsoever full general, repeatable, solution pattern to a ordinarily occurring problem in software blueprint. Some of these usually occurring problems accept implications and solutions detail to object-oriented evolution.

Inheritance and behavioral subtyping [edit]

It is intuitive to assume that inheritance creates a semantic "is a" relationship, and thus to infer that objects instantiated from subclasses tin always exist safely used instead of those instantiated from the superclass. This intuition is unfortunately false in most OOP languages, in item in all those that allow mutable objects. Subtype polymorphism as enforced by the type checker in OOP languages (with mutable objects) cannot guarantee behavioral subtyping in any context. Behavioral subtyping is undecidable in full general, so information technology cannot be implemented by a program (compiler). Class or object hierarchies must exist carefully designed, considering possible wrong uses that cannot exist detected syntactically. This issue is known as the Liskov substitution principle.

Gang of Four pattern patterns [edit]

Design Patterns: Elements of Reusable Object-Oriented Software is an influential book published in 1994 past Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, ofttimes referred to humorously as the "Gang of Four". Along with exploring the capabilities and pitfalls of object-oriented programming, it describes 23 mutual programming bug and patterns for solving them. Every bit of April 2007, the book was in its 36th printing.

The book describes the post-obit patterns:

Creational patterns (5): Manufacturing plant method pattern, Abstract manufacturing plant blueprint, Singleton pattern, Architect pattern, Image pattern
Structural patterns (vii): Adapter pattern, Bridge design, Composite pattern, Decorator pattern, Facade pattern, Flyweight blueprint, Proxy blueprint
Behavioral patterns (11): Chain-of-responsibility pattern, Command pattern, Interpreter pattern, Iterator pattern, Mediator design, Memento pattern, Observer design, Country pattern, Strategy design, Template method pattern, Visitor design

Object-orientation and databases [edit]

Both object-oriented programming and relational database management systems (RDBMSs) are extremely common in software today^[update]. Since relational databases don't shop objects direct (though some RDBMSs have object-oriented features to approximate this), there is a general demand to bridge the two worlds. The trouble of bridging object-oriented programming accesses and data patterns with relational databases is known as object-relational impedance mismatch. There are a number of approaches to cope with this trouble, only no general solution without downsides.^[23] I of the about common approaches is object-relational mapping, as found in IDE languages such as Visual FoxPro and libraries such as Java Data Objects and Ruby on Rails' ActiveRecord.

At that place are also object databases that can be used to replace RDBMSs, but these have not been as technically and commercially successful as RDBMSs.

Real-earth modeling and relationships [edit]

OOP can be used to acquaintance existent-world objects and processes with digital counterparts. However, not everyone agrees that OOP facilitates straight real-earth mapping (see Criticism section) or that real-world mapping is even a worthy goal; Bertrand Meyer argues in Object-Oriented Software Construction ^[24] that a programme is not a model of the world merely a model of some role of the world; "Reality is a cousin twice removed". At the same time, some principal limitations of OOP have been noted.^[25] For example, the circle-ellipse problem is difficult to handle using OOP'south concept of inheritance.

Yet, Niklaus Wirth (who popularized the adage at present known as Wirth's law: "Software is getting slower more speedily than hardware becomes faster") said of OOP in his newspaper, "Good Ideas through the Looking Glass", "This paradigm closely reflects the structure of systems 'in the existent world', and it is therefore well suited to model complex systems with complex behaviours"^[26] (contrast Kiss principle).

Steve Yegge and others noted that natural languages lack the OOP arroyo of strictly prioritizing things (objects/nouns) before actions (methods/verbs).^[27] This problem may crusade OOP to endure more convoluted solutions than procedural programming.^[28]

OOP and control catamenia [edit]

OOP was developed to increase the reusability and maintainability of source lawmaking.^[29] Transparent representation of the control menses had no priority and was meant to be handled past a compiler. With the increasing relevance of parallel hardware and multithreaded coding, developing transparent control menstruation becomes more important, something difficult to attain with OOP.^[30] ^[31] ^[32] ^[33]

Responsibility- vs. data-driven design [edit]

Responsibility-driven design defines classes in terms of a contract, that is, a class should be divers around a responsibility and the information that information technology shares. This is assorted by Wirfs-Brock and Wilkerson with data-driven blueprint, where classes are defined around the data-structures that must be held. The authors hold that responsibleness-driven pattern is preferable.

SOLID and GRASP guidelines [edit]

SOLID is a mnemonic invented by Michael Feathers which spells out five software engineering design principles:

Unmarried responsibleness principle
Open/airtight principle
Liskov substitution principle
Interface segregation principle
Dependency inversion principle

GRASP (Full general Responsibility Assignment Software Patterns) is another fix of guidelines advocated by Craig Larman.

Criticism [edit]

The OOP image has been criticised for a number of reasons, including not coming together its stated goals of reusability and modularity,^[34] ^[35] and for overemphasizing i aspect of software pattern and modeling (data/objects) at the expense of other of import aspects (computation/algorithms).^[36] ^[37]

Luca Cardelli has claimed that OOP code is "intrinsically less efficient" than procedural code, that OOP can take longer to compile, and that OOP languages take "extremely poor modularity properties with respect to grade extension and modification", and tend to be extremely complex.^[34] The latter point is reiterated by Joe Armstrong, the principal inventor of Erlang, who is quoted every bit proverb:^[35]

The problem with object-oriented languages is they've got all this implicit environment that they behave around with them. You wanted a banana merely what you got was a gorilla holding the banana and the entire jungle.

A report past Potok et al. has shown no significant difference in productivity between OOP and procedural approaches.^[38]

Christopher J. Date stated that critical comparing of OOP to other technologies, relational in detail, is difficult because of lack of an agreed-upon and rigorous definition of OOP;^[39] yet, Date and Darwen accept proposed a theoretical foundation on OOP that uses OOP as a kind of customizable type organization to back up RDBMS.^[xl]

In an article Lawrence Krubner claimed that compared to other languages (LISP dialects, functional languages, etc.) OOP languages have no unique strengths, and inflict a heavy burden of unneeded complexity.^[41]

Alexander Stepanov compares object orientation unfavourably to generic programming:^[36]

I find OOP technically unsound. It attempts to decompose the world in terms of interfaces that vary on a single type. To deal with the existent problems you demand multisorted algebras — families of interfaces that bridge multiple types. I find OOP philosophically unsound. It claims that everything is an object. Even if it is true it is not very interesting — maxim that everything is an object is saying naught at all.

Paul Graham has suggested that OOP'southward popularity inside big companies is due to "large (and oft changing) groups of mediocre programmers". Co-ordinate to Graham, the subject area imposed by OOP prevents any ane developer from "doing besides much damage".^[42]

Leo Brodie has suggested a connection between the standalone nature of objects and a tendency to duplicate code^[43] in violation of the don't repeat yourself principle^[44] of software development.

Steve Yegge noted that, as opposed to functional programming:^[45]

Object Oriented Programming puts the Nouns first and foremost. Why would y'all go to such lengths to put i part of speech on a pedestal? Why should one kind of concept take precedence over another? It'due south non as if OOP has of a sudden made verbs less important in the way we really think. It's a strangely skewed perspective.

Rich Hickey, creator of Clojure, described object systems as overly simplistic models of the real world. He emphasized the inability of OOP to model fourth dimension properly, which is getting increasingly problematic as software systems become more concurrent.^[37]

Eric S. Raymond, a Unix programmer and open-source software abet, has been disquisitional of claims that present object-oriented programming equally the "One Truthful Solution", and has written that object-oriented programming languages tend to encourage thickly layered programs that destroy transparency.^[46] Raymond compares this unfavourably to the approach taken with Unix and the C programming linguistic communication.^[46]

Rob Superhighway, a programmer involved in the creation of UTF-8 and Go, has called object-oriented programming "the Roman numerals of computing"^[47] and has said that OOP languages ofttimes shift the focus from data structures and algorithms to types.^[48] Furthermore, he cites an instance of a Java professor whose "idiomatic" solution to a problem was to create six new classes, rather than to simply use a lookup table.^[49]

Formal semantics [edit]

Objects are the run-time entities in an object-oriented organisation. They may correspond a person, a place, a banking company account, a table of information, or any item that the program has to handle.

There accept been several attempts at formalizing the concepts used in object-oriented programming. The following concepts and constructs have been used equally interpretations of OOP concepts:

co algebraic data types^[l]
recursive types
encapsulated country
inheritance
records are basis for understanding objects if function literals tin be stored in fields (similar in functional-programming languages), but the bodily calculi need be considerably more complex to incorporate essential features of OOP. Several extensions of Organization F_<: that deal with mutable objects accept been studied;^[51] these allow both subtype polymorphism and parametric polymorphism (generics)

Attempts to find a consensus definition or theory backside objects have not proven very successful (notwithstanding, see Abadi & Cardelli, A Theory of Objects ^[51] for formal definitions of many OOP concepts and constructs), and frequently diverge widely. For instance, some definitions focus on mental activities, and some on plan structuring. I of the simpler definitions is that OOP is the human action of using "map" data structures or arrays that can contain functions and pointers to other maps, all with some syntactic and scoping saccharide on peak. Inheritance tin can be performed by cloning the maps (sometimes called "prototyping").

See besides [edit]

Comparison of programming languages (object-oriented programming)
Comparing of programming paradigms
Component-based software technology
Design by contract
Object association
Object database
Object model reference
Object modeling linguistic communication
Object-oriented assay and blueprint
Object-relational impedance mismatch (and The Third Manifesto)
Object-relational mapping

Systems [edit]

CADES
Common Object Request Banker Compages (CORBA)
Distributed Component Object Model
Distributed Information Management Architecture
Jeroo

Modeling languages [edit]

IDEF4
Interface description linguistic communication
Lepus3
UML

References [edit]

^ Kindler, E.; Krivy, I. (2011). "Object-Oriented Simulation of systems with sophisticated control". International Journal of General Systems: 313–343.
^ Lewis, John; Loftus, William (2008). Java Software Solutions Foundations of Programming Blueprint 6th ed. Pearson Education Inc. ISBN978-0-321-53205-3. , section 1.6 "Object-Oriented Programming"
^ McCarthy, J.; Brayton, R.; Edwards, D.; Play a joke on, P.; Hodes, L.; Luckham, D.; Maling, K.; Park, D.; Russell, S. (March 1960). "LISP I Programmers Manual" (PDF). Boston, Massachusetts: Artificial Intelligence Group, M.I.T. Computation Center and Research Laboratory: 88f. Archived from the original (PDF) on 17 July 2010. In the local K.I.T. patois, clan lists [of diminutive symbols] are also referred to as "belongings lists", and diminutive symbols are sometimes called "objects".
^ McCarthy, John; Abrahams, Paul Westward.; Edwards, Daniel J.; Hart, swapnil d.; Levin, Michael I. (1962). LISP one.5 Developer's Manual. MIT Press. p. 105. ISBN978-0-262-13011-0. Object — a synonym for atomic symbol
^ ^a ^b "Dr. Alan Kay on the Meaning of "Object-Oriented Programming"". 2003. Retrieved eleven February 2010.
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External links [edit]

Introduction to Object Oriented Programming Concepts (OOP) and More past L.W.C. Nirosh
Word on Cons of OOP
OOP Concepts (Java Tutorials)

oliverhealf1938.blogspot.com

Source: https://en.wikipedia.org/wiki/Object-oriented_programming